Hard disk drives are common information storage devices. FIG. 1a provides an illustration of a typical disk drive unit 100 essentially consisting of a series of rotatable disks 101 mounted on a spindle motor 102, and a Head Stack Assembly (HSA) 130 which is rotatable about an actuator arm axis 105 for accessing data tracks on disks during seeking. The HSA 130 includes at least one drive arm 104 and a head gimbal assembly (HGA) 150. Typically, a spindling voice-coil motor (VCM) is provided for controlling the motion of the drive arm 104.
Referring to FIG. 1b, the HGA 150 includes a slider having a thermally assisted head 110, and a suspension 190 to load or suspend the slider 103 thereon. The suspension 190 includes a load beam 106, a base plate 108, a hinge 107 and a flexure 109, all of which are assembled together. When the disk drive is on, a spindle motor 102 will rotate the disk 101 at a high speed, and the slider 103 will fly above the disk 101 due to the air pressure drawn by the rotated disk 101. The slider 103 moves across the surface of the disk 101 in the radius direction under the control of the VCM. With a different track, the slider 103 can read data from or write data to the disk 101.
Referring to FIG. 1c, the thermally assisted head slider 103 has a substrate 1031 with an air bearing surface (ABS) 1032 processed so as to provide an appropriate flying height. The thermally assisted magnetic head 110 includes a write portion 121 having a write element 123 and read portion 122 having a read element 124. And a thermal energy source 111 is mounted on the substrate 1031 for providing heat energy to the thermally assisted magnetic head 110, such as a laser diode at or near the location of the write portion 121. Conventionally, the thermal energy source is bonded to the substrate 1031 via solders, for example. This thermal energy source provides energy to a portion of the magnetic recording medium, which reduces the medium's coercivity. After that, writing is performed by applying write magnetic field to the heated portion; therefore the writing operation is facilitated. Generally, the thermally assisted magnetic head 110 further includes a waveguide 125 and a plasmon antenna (PA) or a plasmon generator (PG) 127 located near the write element 123. The waveguide 125 is provided for guiding the laser light to the ABS 1032 by a surface of the PG 127, thereby providing near-field light, instead of directly applying the laser light to an element that generate near-field light. Such a PG and a waveguide are disclosed, for example, in US Patent Publication No 2010/0103553 A1.
Conventionally, for preventing the read portion 122 and the write portion 121 from lacking magnetic or being impacted by the external environment, a over coat made by diamond-like carbon (DLC) for example, is covered on the top of all elements mentioned above to form the ABS 1032. However, such a DLC layer couldn't endure the high temperature during the writing operation for the thermally assisted magnetic head slider 103, which may absorb the near-field light propagated by the PG 127 significantly and even may be disappeared. Thus the DLC layer has been replaced with a coat layer 131 with lower extinction coefficient (light absorption index) of complex refraction index made by SiOx, SiNx, SiOxNy, TaOx, TaNx, TaOxNy, hydrogenated amorphous carbon in the thermally assisted magnetic head slider, to cover on the opposed-to-magnetic medium recording surfaces of all elements mentioned above to form the ABS 1032, so as to obtain a good thermal stability for writing.
However, since the opposed-to-magnetic medium recording surfaces of the write element 123, the waveguide 125 and the read element 124 which are corrosive material are also covered by the coat layer 131 made by oxide material except for the PG 127, thus the corrosive materials such as the write element 123, the waveguide 125 and the read element 124 may be corroded by oxygen due to the coat layer 131 has poorer oxygen barrier ability compared to the DLC layer. Furthermore, the coat layer 131 made by oxide material has a smaller hardness than the DLC layer, which may be worn after frequent contacting the medium when reading or writing, thus is not suitable for using for long.
Accordingly, it is desired to provide improved manufacturing methods of a write portion and a thermally assisted magnetic head slider to overcome the above-mentioned drawbacks.